I'm 48 years old, just had front teeth crowned. How many times can I have them crowned?

I had veneers one cracked my dentist said there was not enough enamel to bond to so I needed crowns. I am worried how many times I can replace the crowns. He did both my teeth so they would match. I did not have enough time to think about this procedure because my veneer was cracked. I wish I would of thought more about it before having crowns put on.